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eXStatA Build Thread II - Page 37

post #541 of 566

Does anyone have boards for a hybrid + PSU build? Interested in buying if so, not sure when the next group buy will be.

post #542 of 566

contact me via IM

post #543 of 566

One of these days I'll get my stuffed hybrid boards installed in my case.  After that then I'll have an SS amp board set and full BOM of parts for the amp section for sale (but I think the PSU board was used to fix my old amp - I have to check).  If the hybrid boards don't work then EVERYTHING might have to go, since I can't build the SS amp.

post #544 of 566

It's been too quiet arround here for too long ;-)

 

 

My exstata is making trouble since yesterday.

 

I took out the boards to change some of the input wiring in the case.

(Source selector and loop out stuff)

 

I also cleaned the boards softly with a soft paint brush to remove some dust.

 

The I installed everything back and began with the initial check.

 

 

Power supply is ok - but the two boards are showing high offset values!

Everything worked perfectly before, now I'm unable to get the voltages

down close to 0V before the end of the trimpots is reached.

 

One board is showing ~40V between + and -, the other one

shows more than 150V and rising (I switched off then).

 

 

So what the H*** is going on here?

I can't imagine having destroyed something with a paint-brush!

post #545 of 566

*push*

 

I'll dismount the boards again today and clean them with some isopropanol.

 

Maybe that helps.

post #546 of 566

We'll  -fixed it ;-)

 

One board defenitely had a problem - maybe due to dirt or whatever.

 

The other part of problem was me!

I mixed up the two trimpots - so this could not work.

 

 

Now it's sitting here at my desk, warming up and the voltages are ok.

 

 

Now let's hope I have not mixed up L / R channels somewhere im my wiring :-D

post #547 of 566

I took my solid state exstata out to do some measurements and now I am a bit worried about what I saw. I have been using a function generator which has a bigger output voltage swing than the ipod I usually use (around 1V for one, 2,5V for the other). At full output (which was something like 40 or 50V peak to peak) the red diodes in the power supply aren't lit as they should ; One goes blank while the other oscillates.

So here are my two questions. How normal is it for the diodes in the power supply to act this way ? And secondly, how come the amp starts to behave  weirdly at only 50V peak to peak ? Have other builders experienced this (should I question my own building skills ? ) ?

 

(I might to have to check again, but I really think it is 50V peak to peak. Coming from a ±300V powered amp it seems a bit low. Should the exstata be powered with something like a 10V source ? )

post #548 of 566
From memory, those LEDs light up when current is running through the shunt regs. So I wonder whether as the output voltage goes up, current consumption increases, and your PSU is dropping out of regulation.

If this is the case, increasing the current through the first stage of the PSU by a small amount might help.
post #549 of 566

Thank you Beefy. So toying with P1 and P2 in the power supply it is biggrin.gif I hope it is going to be tough enough to handle it.

 

Edit : I checked T1-T2 and T3-T4 in the power supply. It is in the range Alex Cavalli suggested. Another thing, I plugged the eXstata into my otl tube amp to have moar input voltage (up to 6VAC) so that the output delivers around 600vac max. The red diodes in the power supply are not oscillating as I described before. I have not a clue of what is going on ... maybe the fact of the function generator being a monochromatic source plays a role ?

 

edit2 :  I am pretty sure I wasn't careful enough with ground sharing.I probably shorcut one of the output while measuring with the oscilloscope which lead to stupid results ... I will have to try again to make sure it was indeed my own stupidity ...


Edited by bidoux - 4/1/13 at 4:23am
post #550 of 566

My exstata is showing some strange behavior this evening.

 

I have a kind of humming/buzzing sound, changing in toneheigt over time.

It disappears are becomes at least almost unhearable when I touch

the case or the metal parts of the cinch connectors.

 

It's only the right channel.

 

What might that be?

post #551 of 566

Push

post #552 of 566

Either the case is not grounded or you've got a ground loop.

post #553 of 566

Does anyone here have the 'phone jack pinout diagram used for this amp? I checked the wiki, but the pix there contradict themselves. I'm finishing up the build of

an eXStaTa for a friend, and don't want to wreck his 950's. Thanks.


Edited by funch - 8/1/13 at 4:52pm
post #554 of 566
post #555 of 566

Thanks sachu. I just traced the wiring on the 'phones (ESP 950's), and found that the amp jack diagram in the second link has the L- and R- reversed.

Pin 4 should be R-, pin 5 L-. That's what had me baffled. I had to use a very small needle to pierce the cable so I could verifiy that they were switched

on the diagram.

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